1. Field of the Invention
The present invention relates to a method for controlling a fuel metering system of an internal combustion engine, which system determines the quantity of the fuel to be delivered to the power cylinders of the engine.
2. Description of Background Information
In an electronic control system for a fuel metering system of an internal combustion engine, the quantity of fuel to be supplied to the engine power cylinder via a fuel supply means such as a carburetor or a fuel injector, is calculated in accordance with a plurality of parameters so as to optimize the engine operation under various conditions such as cold starting, acceleration, deceleration and so on. The method of calculation is such that the fundamental value of the quantity of fuel supply is first calculated in accordance with basic parameters such as the engine speed and the flow of the air drawn into the engine. In order to provide an accurate control, an increment or decrement correction value is further calculated in accordance with auxiliary parameters such as the engine coolant temperature and a sign indicative of the presence of a transitional state of the engine operation, and the thus calculated correction value is multiplied or added to the fundamental value in order to realize a desired control of the fuel supply.
In prior art, it was general to construct the control system so that a plurality of increment values or increment coefficients are independently calculated in response to each of the engine parameters depending on the state of the engine operation. Therefore, if two or more increment values are overlapped in some engine operational state, the total amount of the increment would become excessibly higher than an increment value actually needed. Such an excessive increase of the fuel supply would result in an over rich air-fuel mixture which deteriorates the engine performance and the fuel consumption characteristics and further it might cause an adverse effect upon the emission characteristics.